In his debut, it is revealed that Querius was apparently a student of King Plumber, having come to him to train. King Plumber was not able to foster his ambitions, and they got the best of Querius, making him the villain of the story.
In the New Fantendoverse, Querius appears to be some kind of minor god that came into his own being, although he was infected with the Hivemind virus and was able to fight it, but with the permanent side-effect of not mentally not being able to hurt The Threat. The Threat inducted him into her forces not too soon afterwards.
In his debut, Querius is played up as a goofy evil cartoon villain, although his main defining character trait is his out-of-control ambition and need for more power, fusing himself with The Beast to gather more power to fight the united heroes. His determination, having being defeated multiple times during the story, ends up getting him killed permanently in the end, although he has the last laugh by opening a portal to the black void.
Post-Shattering, Querius is seen as one of the Threat's forces, working aside her. However, his ambition far outweighs her's, wanting to build his own universe using parts of the current one. He seems to outright despise The Threat, having been infected with her Hivemind disease but being able to fight it off, although this had the side effect of mentally being unable to harm her.
Powers and Abilities
Querius is a vastly powerful being, able to construct portals that suck in his opponents and leave them stranded in a featureless, inescapable black void dimension. He is also able to fuse other characters as well as himself to whoever he deems as a good host for his power. He also is able to move people telekinetically on a mass scale, as seen in Fantendo Smash Bros. Victory.
Querius appears as the a main antagonist in Fantendo Heroes UNITE!!!.
Querius appears as a antagonist in Fantendo Smash Bros. Victory's story mode Days of Victory. He is first introduced after Unten and Pesh defeat The Beast, where his power and motives are explained, suggesting to the group that they don't interfere with him in the future.